Increasing women’s voice and agency is widely recognized as a key strategy to reduce gender inequalities and improve health outcomes. Although recent studies have found associations between women's autonomy and a number of health outcomes, fundamental issues regarding adequate measurement of women's autonomy remain. The Relative Autonomy Index (RAI) provides a direct measure of motivational autonomy. It expresses the extent to which a woman faces coercive or internalized social pressure to undertake domain-specific actions. This addresses a key critique of current measures of autonomy, which focus on decision-making or ignore women’s values. This paper examines the measurement properties and added value of a number of domain-specific RAIs using new nationally representative data from The Republic of Chad. A striking finding is that women on average have less autonomous motivation in all eight domains compared to their male counterparts. The paper also investigates the relationship between domain-specific RAIs and breastfeeding, a contextually relevant behavior that affects children's health.